Process of forming lenses



H. W. HILL.

PROCESS OF FORMING LENSES.

APPLICATION FILED SEPT. 13. 19!].

1,332,724 Patented Mar. 2,1920.

INVENIOR HA re 12 V w. H/L L.

more sas [a w r "'m- 3 ra T? an if HARRY WILLIAM HILL, OF SOUTHBRIDGE,MASSACHUSETTS, ASSIGNOE TO AMERICAN OPTICAL COMPANY, OF SOUTHBRIDGE,MASSACHUSETTS, A VOLUNTARY ASSOCIA- TION OF MASSACHUSETTS.

PROCESS OF FORMING LEEUSES.

Specification of Letters Patent.

Patented Mar. 2,

To all 1072,0227. it may concern:

Be it known that I, HARRY V. HILL, a citizen of the United States,residing at Southbridge. in'the county of .Vorcester and State ofMassachusetts, have invented certain new and'useful Improvements inProcof Forming Lenses, of which the following is a specification.

My invention relates to improvements in processes for formin lenses andhas particular reference to the formation of a rough. finished or shapedlens blank from the rough glass stock.

One of the leading objects of the present invention is the provision ofan improved process by which the rough piece of ma terial may be.quickly and satisfactorily brought from its rough condition into asemi-finished form and which process will further serve to eliminate toa very great extent bubbles. striae or other weaknesses or defects inthe glass, and will relieve the blanks of the strains present inordinarily molded lenses, such as have been known in the prior art.

A further object of the present invention is the provision of animproved process embodying a continuous series of. steps preferablyperformed in immediate sequence, whereby the glass from the time it isstarted in rough condition until it reaches finished annealed form isnot allowed to become cold but is maintained in a greater or less heatedstate, conserving the number of heat units necessary to complete theprocess. and elimi- Dating strains and defects Which might be presentin. the glass were the same chilled or allowed to chill between theseveral major operations thereon.

Other objects and advantages of my improved process should be readilyapparent by reference to the followingspecifications taken in connectionwith the accompanying diag 'ammatic. drawing, and it will be understoodthat I may make any modifications or variationsin the performance of thesteps of the process within the scope of the appended claims withoutdeparting from or exceeding the spirit of my invention.

ln the drawings I have diagrammatically illustrated an arrangement ofapparatus for carrying out of several steps of my process, but it willbe understood that the process is capable of accomplishment by manydifferent forms of apparatus or of: perfor1nance partially through theuse of aimaratus and partially manually.

In the carrying out of my improved process the steps are preferablyfollows: i first place the rough piece of glass 1 of approximately theright or weight to produce the desired finished art cle within asuitable heatingmember. such as the oven 2 shown in the drawings. Forconvenience I have illustrated the stock 1 a? placed upon a rotatinptable 3. the essential being, however, that it is placed within a sourceof heat and is there gradually heated, "cferably y movement through anoven having a nuniber of heating portions or the like so it is subjectedto a gradually increasing heat until it is brought to the desiredtemperature, it being however. at all. times main tained;at atemperature below its melting point so that it will be in a softened butnot in a molten condition. The stock having; been thus suitably heated lpreferably puddle it, as by the puddles 3 to eliminate bubbles stria;and other defects of a similar nature frequently present in the roughstock, roughly shaping it during the puddling and then convey it intothe mold i where itwili be operated on by the plunger 5 to cause it toassume the shape of the mold and plunger. It is to be understood thatthe shape of the glass up to the time of reaching the mohl is immaterialand in the accompanying: drawings the material is shown diagrauaticmerely for the purpose of illustration. In this transferringoperation. however, 1: subject it to a continued heat, which while not\increasing the temperature of the stock it is shifted from the furnacewill maintain at the desired temperature and prevent any chilling duringthe shifting operation. For convenience in understanding this I haveillustrated the automatic carrier 6 and certain gas or other heatingburners '2 directing their heat against the stock 1 as is shifted alongthe eonvey'en. although it will be understood that any other suitablemeans for maintaining; the parts at the right temperature during theshifting operation may be employed without in anywise varying theprocess.

It will be understood that at the time of the puddling operation theglass is in a semifluid or plastic condition, such that While itsnatural viscosity will tend to keep it from 'into substantially desiredform the stock in question and in this stirring or shifting of themolecules or parts of the glass will tend to force out any bubbles whichmay be formed in the body thereof rendering the same in compact shape,the heating action subsequent to this point being insuil'icient tomaterially affect the shape of the blank as roduced during the puddlingoperation.

y process further contemplates the retaining of the molded stock 1within the mold 4 for a certain period after the actual pressing so thatit may have a chance to become somewhat cooled and less liable to changeof shape or distortion when it is removed from the mold, after which inthe carrying out of my process I remove the shaped blank 1' from themold, place it in a second suitable chute or conveyer 8 where it'may beagain subjected to a slight heat, as from the heating nozzle or othersource of heat 9, after which and as the final step in the carrying outof my process I anneal the heated blank as by placing it within anannealing chamber 10, the chamber being so constructed that it willreceive the warm blank from the transfer member 8, will gradually raisethe tem 'mrature of the blank to the required point to'anne al the same,will maintain it for the necessary period at an annealing ten'iperature,and eventually discharge the blank in substantially cold condition,having allowed it to gradually cool While Within or passing through theannealing chamber, the cold blank emerging or being brought out andplaced in a suitable container at 11.

From the foregoing description the essentials of my improved processshould be apparent, and it will be seen that my process contemplatesgradually increasing the temperature, preferably of a rough piece ofglass stockto a plastic condition, puddling and shaping the stock whileplastic, main-.

taining it in this plastic condition while transferring it from the mainheating member to a mold, pressing it within the mold to assume thedesired shape. retaining it in the mold till it has substantially set tothis shape, removing it from the mold, initially heating it subsequentto its removal to the mold, annealing the blank by gradually raising andcooling its temperature and removing the cooled blank trom the annealcr.

I claim:

1. The process of forming lens blanks. including heating stock to aplastic condition, puddling the plastic stock, molding the puddled stockand annealing the shaped blank.

2. The process of forming a lens including heating the stock to aplastic condition, puddling the stock during the heating operation,pressing the stock into form after paddling and while plastic andannealing the formed lens, before it has entirely cooled from theinitial heating.

3. The process of forming a lens including subjecting the stock to anintermittent series of heating actions to prevent cooling of the lensduring the process, one of the initial beatings being sufiicient torender the lens plastic. puddling and subsequently molding the lenswhile plastic. and subsequently annealing the lens by the subsequentheating actions.

In testimony whereof l have atlixed my signature, in presence of. twowitnesses.

HARRY WILLIAM HILL.

Witnesses Enrrn M. ITA'LV'ORSEN, ESTHER M. LArLnR.

